Digital Light & Color

I'm reasonably familiar with creating masks and using them to separate one element-of-interest in an image from the rest of the image. Thus allowing alteration of the element-of-interest without affecting the rest of the image and vice-versa.
What I can't figure out is how to keep the element-of-interest as is and how to make the rest of the image transparent so that when printed on a transparancy only the element-of-interst is printed, leaving the rest of the transparancy in its original fully transparent condition.

The obvious approach of trying to print with the mask 'active' on the element-of-interest seems to have no effect. I haven't actually printed anything out because the entire image is shown in the print dialog box.

Any tips, anyone?

Mike.

Here is what I would do:

1- create a mask to preserve those areas I want to print
2- a) open the "Filter" transformation and set the mask (black "amount" slider to 0% - "white" amount slider to 100%)
b) set the "Filter" property to solid white
c) set the "Method" to "subtractive"
d) hit "OK" Everything not covered by the mask should go to white
3- Save and print - since very few printers can print white those areas will be transparent on the printing film

Hope this helps.

Brian

Brian,

Many thanks - did the trick very nicely. I imagine that getting the background dead white by any other means would work just as well.
To get my printer (Epson R290) to recognise the transparency I had to use another trick (tip picked up on the Internet) which was to tape the transparancy to a sheet of white paper along the top leading edge using thin double sided tape. This also worked well.
The only thing that wasn't 'perfect' was the printing itself. Some blotchiness in one area (which is not present when printing opaque print media). I should say that 'transparency' does not show up in the drop down list of available (media) types in the printer preferences (of the Epson R290) so that in itself may be sufficient explanation. It did mean I had to guess what best (media) type to select. I chose Epson glossy, with 'best photo' and 'photo enhance' also selected. Another media type might have produced a better result.
Happily the result is perfectly adequate for the application. My wife is going to paint a portrait from a photo and the transparancy overlay is a convenient way of checking that the critical 'face recognition' points are in the right relationship to one another as the portrait progresses.

Mike.

Glad to be of service Mike,

I'm not familiar with the Epson R290 but it probably uses "dye" type inks.
In my experience these inks don't work as well as "pigment" inks on transparencies.

Brian

You can also use the Composite transformation, setting the Overlay to the solid color you want the background to be. Set the input image mask to cover the region you don't want covered and set the Overlay Amount to 100% (or less if you want the background to show through the solid color partially.

Brian/Jonathan,

Thank you both. I had a feeling when I posted the question that the solution might be embarrassingly simple. But the fact that most printers can't print white hadn't crossed my mind for a moment.
Yes, the R290 uses 6 cartridge Claria inks. From what I can gather these are dye based as Epson's pigment based inks appear to be the Durabrite range, and the Durabrite using printers 4 cartridge only.

Mike.

Mike,

The Epson Claria inks are definitely dye-based. Epson offers various pigment-based inks, a.o. the Durabrite, and printers with 4 ink and multiple-ink systems. So the pigment systems are not limited to 4 colors.
I suppose that your transparancy is suitable for water based inkjet. Otherwise you wil certainly run into trouble. By selecting the setting for glossy photo paper you also selected the maximum ink load, since other papers in general don't accept that much ink. Maybe it is too much for your transparancy.
I'm not sure what you mean by "blotchiness" (I'm no english speaker), but maybe the ink and media don't match and you observe coalescence, probably in dark areas where the ink load is highest. In that case you will probably need a different type of transparancy. Selecting a different setting like matt coated paper might save your day, but as the maximum amount of ink will be less the contrast of the transparancy will be less as well.